Oxygen carrier for detergent compositions

ABSTRACT

A FAST DISSOLVING, NONSEGREGATING OXYGEN CARRIER FOR GRANULAR DETERGENTS IS DISCLOSED, CONSISTING ESSENTIALLY OF 4.5% TO 59% FINELY DIVIDED PEROXYHYDRATE SALT IMBEDDED IN 20% TO 88% OF A WATER-SOLUBLE WAXY SOLID, SAID WAXY SOLID ADHERING TO 4.5% TO 50% OF GRANULAR BORAX SUBSTRATE, SAID SUBSTRATE HAVING A BULK DENSITY OF 0.03 TO 0.56 G/.CC. AND A PARTICLE SIZE BETWEEN 0.074 MM. AND 3.36 MM. A PROCESS FOR PREPARING THE OXYGEN CARRIER IS ALSO DISCLOSED IN WHICH THE WAXY SOLID IS DISSOLVED IN A VOLATILE ORGANIC SOLVENT, THE PEROXYHYDRATE SALT IS SLURRIED INTO THE SOLUTION, AND THE SLURRY IS SPRAYED ONTO A FALLING CURTAIN OF THE GRANULAR BORAX.

3,562,171 OXYGEN CARRKER FOR DETERGENT CGMPUSTTHONS Robert A. Guida, Wyoming, Ohio, assignor to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio N Drawing. Filed Dec. 31, 1968, Ser. No. 789,003 lint. Q1. Clld 7/54 US. Cl. 252-186 Claims ABSTRACT (IF THE DESCLOSURE A fast dissolving, nonsegregating oxygen carrier for granular detergents is disclosed, consisting essentially of 4.5% to 59% finely divided peroxyhydrate salt imbedded in to 88% of a water-soluble waxy solid, said waxy solid adhering to 4.5% to of granular borax substrate, said substrate having a bulk density of 0.03 to 0.56 g./cc. and a particle size between 0.074 mm. and 3.36 mm. A process for preparing the oxygen carrier is also disclosed in which the waxy solid is dissolved in a volatile organic solvent, the peroxyhydrate salt is slurried into the solution, and the slurry is sprayed onto a falling curtain of the granular borax.

This invention relates to a fast-dissolving, non-segregating oxygen bleach carrier designed for mixing with detergent granules, and the process for preparing said oxygen carrier.

Mechanical mixtures of granular detergents, especially spray-dried detergents, and crystalline inorganic peroxyhydrate salts are well known. The peroxyhydrate salt contains hydrogen peroxide bleach within its crystal structure, and therefore serves as a carrier for incorporating active oxygen bleach into detergent compositions. Sodium perborate tetrahydrate is the most common peroxyhydrate salt used in these mixtures These mechanical mixtures, because of differences in density and particle size between the peroxyhydrate salt and the detergent, have the disadvantage of tending to segregate during handling, so that the peroxyhydrate salt is not uniformly distributed throughout the entire composition when it reaches the consumer. If a relatively large particle size of peroxyhydrate salt is used to reduce segregation, difficulty is encountered in dissolving the peroxyhydrate salt when the composition is used by the consumer. If a fine particle size of peroxyhydrate salt is used in order to obtain fast dissolving, unacceptable segregation occurs.

An object of this invention is to formulate a fast-dissolving, oxygen bleach carrier which can be produced at a density and particle size which approximately match that of the detergent granule with which it is to be mixed.

Another object of the invention is to provide an efficient process by which such an oxygen bleach carrier can be made.

The objects of this invention can be accomplished by a process comprising the steps of (1) dissolving a watersoluble, waxy solid in a volatile solvent, (2) adding a finely divided peroxyhydrate salt to the solution to form a slurry and (3) spraying this slurry onto a granular borax substrate of a preselected bulk density and particle size (described hereinafter as puffed borax), said substrate being formed into a falling curtain to receive the spray-on. Upon contact with the puffed borax, the volatile solvent evaporates, leaving behind a crisp, free flowing, fast dissolving granular composition, comprising a puffed borax substrate with finely divided crystalline peroxyhydrate salt imbedded in an outer coating of water-soluble, waxy solid adhering to said substrate.

The puffed borax used in the present invention can 3,562,171 Patented Feb. 9, 1971 be produced by the process disclosed in an article by R. C. Rhees et al., Soap and Chemical Specialties. vol. XLll, January 1966. pages 58-61 and 118-120. This article describes how borax particles which normally have a bulk density of about 1 g./cc., can be made to puff by rapid heating, and thus be greatly reduced in bulk density. By proper selection of operating conditions, the puffed borax can be produced within a wide range of particle size and bulk density, Densities between 0.03 and 0.56 g./cc. have been obtained. To be useful as a substrate for a nonsegregating oxygen carrier intended for mixing with detergent granules, the puffed borax substrate must have a bulk density and particle size such that the resulting carrier has particle characteristics approximating those of the detergent granules with which it is to be mixed. Such detergent granules generally have a particle size within the range of 0.074 mm. to 3.36 mm. (through No. 6 and on No. 200U.S. Standard Sieve Series), and a bulk density of 0.2 to 0.8 g./cc. A nonsegregating oxygen bleach carrier must also have particle size and density which fall within these ranges. The detergent granules with which the oxygen bleach carrier is to be mixed will have a bulk density within the range specified above. However, the detergent will comprise granules which are not uniform in size, but which have a particle size distribution within the range mentioned above. In order to reduce segregation problerns, the bulk density and particle size distribution of the puffed borax substrate should be chosen so that the resulting oxygen bleach carrier will have a bulk density and particle size distribution which match closely those of the detergent granules with which the carirer is mixed. In determining the bulk density of puffed borax to be used as a substrate, due regard must be had to the increase in density which will occur as a result of the addition of organic solid and peroxyhydrate salt to the substrate. Therefore a puffed borax density less than that of the detergent granules will generally be chosen; precisely how much less depends on the amount of peroxyhydrate salt intended to be added to the substrate. For instance, see Example I below. where pufied borax of 0.2 g./cc. bulk density was used to obtain a carrier having a bulk density of 0.35 g./cc. The addition of peroxyhydrate salt to the puffed borax substrate has little effect on the particle size of the substrate, because the peroxyhydrate salt/waxy solid matrix primarily fills the voids in the irregular surface of the puffed borax granules. Therefore, the particle size distribution of the pulled borax chosen for use as a substrate should be approximately the same as that of the detergent granules with which the oxygen bleach carrier is mixed.

In addition to its function as a substrate in the oxygen bleach carrier of the present invention, the borax also serves a useful function as a pH buffer in the detergent composition to which the oxygen bleach carrier is added.

The water-soluble, waxy solid used in the present invention to cause the peroxyhydrate salt to adhere to the puiied borax substrate, can be selected from a wide range of such materials well known in the detergent art. The only requirement is that it be water-soluble and that it be a waxy solid at ambient temperatures (i.e.. at temperatures between 18 C. to 38 C.). Water solubility is necessary to facilitate rapid dissolving 0f the entire carrier composition, and the solid waxy physical state at ambient temperatures is necessary to keep the peroxyhydrate salt in adhesion to the puffed borax substrate, and at the same time keep the oxygen carrier in the form of a dry free flowing granule.

There are many such water-soluble, waxy solids which are suitable for the purpose of this invention, but the more suitable ones are solid condensation products of a low molecular weight alkylene oxide and a hydrophobic moiety. Preferred water-soluble, waxy, solid condensation products are those of 650 moles of ethylene oxide with one mole of any of the following: (1) fatty alcohols of 22 carbon atom chain length; (2) fatty acid amides of 10-22 carbon atom chain length and (3) alkyl phenols having 812 carbon atoms in the alkyl chain. Several specific examples are as follows: lauryl alcohol condensed with 45 moles of ethylene oxide, tallow alcohol condensed with 30 moles of ethylene oxide, oleyl alcohol condensed with 20 moles of ethylene oxide, tallow fatty acid amide condensed with moles of ethylene oxide, and nonyl phenol condensed with 15 moles of ethylene oxide. These materials, in addition to causing the fine particles of peroxyhydrate salt to adhere to the puffed borax substrate, have detergent properties of their own, and therefore contribute to the cleaning performance of the detergent granules to which the oxygen bleach carrier of this invention is added. Also, in causing the peroxyhydrate salt to adhere to the pulfed borax, these waxy materials form a coating around the peroxyhydrate salt thus reducing or preventing undesirable interactions between the peroxyhydrate salt and other ingredients (e.g., enzymes and free water) which may be present in the detergent granule. The above materials have been mentioned only as examples of water-soluble, Waxy solids which are particularly suitable for use in this invention, and there is no intention that the invention be limited to those mentioned. One skilled in the art could readily select many more such water-soluble, waxy solids which would be suitable.

The peroxyhydrate salts used must have a particle size of less than 0.210 mm. (No. 70 U.S. Standard Sieve Series) in order to obtain the fast dissolving carrier of this invention, and greater than 0.044 mm. (No. 325 U.S. Standard Screen) in order to avoid excessive dust problems in handling. Preferably the particle size should be between 0.149 mm. (No. 100 U.S. Standard Sieve Series) and 0.063 mm. (No. 230 U.S. Standard Sieve Series). These salts can be selected from the group consisting of the peroxyhydrates of the alkali metal borates, carbonates, silicates and phosphates, particularly the sodium and potassium salts. These salts are called peroxyhydrates because they contain hydrogen peroxide in their crystalline structure. Well known examples from this group are the sodium perborate and sodium percarbonate commonly used in the detergent industry.

The solvent used in this invention should have a boiling point within the range of about 55 C. to 110 C. so as to be in the liquid state and easily handled at the ambient temperatures under which this invention is carried out (18 C. to 38 C. or below), and to evaporate readily after application to the puffed borax substrate. Too much volatility will result in excess evaporation before the spray-0n, and insufficient volatility will result in the carrier composition being sticky and nonfree-flowing after the spray-on. Any of the many well known organic liquids, having the above characteristics and being capable of dissolving the water-soluble, waxy solids used in this invention, are suitable for use in the process of this invention. Such liquids should have evaporation rates no faster than that of acetone and no slower than that of isopropanol (rates ranging from 110 to 1160). See tables in the Kirk Othmer Encyclopedia of Chemical Technology, volume 12, pages 6667 et seq. (1954), incorporated herein by reference. Specific examples of such suitable solvents are: lower monohydric alcohols such as methanol, ethanol, propanol and isopropanol, lower ketones such as acetone and methyl ethyl ketone, and low molecular weight esters such as ethyl acetate and isopropyl acetate. Organic solvents, such as ethyl formate and ethyl ether are too volatile and organic solvents such as cyclohexanone, n-butyl alcohol nbutyl acetate, dimethyl snlfoxide and dimethyl formamide, have boiling points which are too high.

This invention may be practiced in the following manner. The water-soluble waxy material is dissolved in the volatile solvent defined above. Into this solution is slurried an amount of fine granular peroxyhydrate salt, preferably sodium perborate, which is 0.1 to 1.5 and preferably 0.25 to 1.0 times the weight of the waxy material. This slurry is then sprayed through an atomizing nozzle onto a puffed borax substrate of preselected bulk density and particle size distribution the amount of said substrate being from 0.05 to 1.0 and preferably from 0.1 to 0.4 times the combined weight of the water-soluble, waxy solid and peroxyhydrate salt contained in the slurry. These ranges of ratios result in compositions consisting essentially of about 20% to 88% water-soluble waxy solid, 4.5% to 59% peroxyhydrate salt, and 4.5 to 50% borax. In order to obtain a uniform coating of the slurry on the substrate, it is preferred to form the substrate into a falling curtain, preferably by rotating it in a baffled drum, while the slurry is being sprayed onto it. The resulting product is a crisp, free-flowing, fast-dissolving granule, comprising a puffed borax substrate with finely divided crystalline peroxyhydrate salt imbedded in an outer coating of water-soluble waxy solid adhering to said substrate.

The practice of the invention will be elucidated by the following examples. All parts and percentages herein are by weight unless otherwise specified.

EXAMPLE I Seventy-five pounds of the condensation product of one mole of coconut fatty alcohol and moles of ethylene oxide were dissolved in 45 pounds of ethanol. 30 pounds of sodium perborate having a particle size between 0.074 mm. and 0.063 mm. (through No. 200 and on No. 230 Standard U.S. Sieve) was slurried into this solution. This slurry was then sprayed through an atomizing nozzle onto 30 pounds of a puffed borax substrate having a particle size distribution between 1.2 and 0.30 mm, (through 16 mesh and on mesh U.S. Standard Sieve Series), and a bulk density of 0.2 g./ cc. The spray-on was accomplished by spraying the slurry into a falling curtain of puffed borax formed in a rotating baffled drum.

The resulting product was a crisp, free-flowing, fastdissolving granular carrier comprising approximately coconut alcohol/ethylene oxide condensate, 22.5% perborate and 22.5% puffed borax. The carrier had a bulk density of 0.35 g./cc. and a particle size distribution between 1.2 and 0.30 mm., and showed essentially no segregation when mixed with detergent granules of comparable particle size and density.

If sodium percarbonate is substituted for sodium perborate in the oxygen carrier of this example, with all other conditions remaining the same, a composition with essentially the same characteristics is obtained.

EXAMPLE II An oxygen carrier is prepared having the same com position as that in Example I except that the condensation product of one mole tallow fatty alcohol and 30 moles of ethylene oxide is substituted for the condensation product of one mole of coconut fatty alcohol and 45 moles of ethylene oxide. The process used is identical to that in Example I except that methanol is substituted for ethanol. The resulting product is a crisp, free-flowing, fast-dissolving granule showing essentially no segregation when mixed with detergent granules of comparable particle size and density. An oxygen carrier of substantially the same characteristics is also obtained when the condensation product of tallow fatty alcohol and 30 moles of ethylene oxide is replaced by the condensation product of nonyl phenol and 15 moles of ethylene oxide, oleyl alcohol condensed with 20 moles of ethylene oxide or tallow fatty acid amide condensed with 15 moles of ethylene oxide.

What is claimed is:

1. A granular oxygen bleach carrier consisting essentially of 4.5% to 59% of a peroxyhydrate salt having a particle size of 0.044 to 0.210 mm. and selected from the group consisting of the peroxyhydrates of the alkali metal borates, carbonates, silicates and phosphates, imbedded in 20% to 88% of a water-soluble, waxy, compound which is solid at temperatures between 18 C. and 38 C. and are selected from the group consisting of solid condensation products of 6-50 moles of ethylene oxide with one mole of any one of the following: (1) fatty alcohols of -22 carbon atom chain length; ,(2) fatty acid amides of 10-22 carbon atom chain length and (3) alkyl phenols having 8-12 carbon atoms in the alkyl chain, said waxy compound adhering to 4.5% to 50% granular borax having a bulk density between 0.03 and 0.56 g./cc. and a particle size between 0.074 mm. and 3.36 mm.

2. The composition of claim 1 wherein the peroxyhydrate salt is sodium perborate.

3. The composition of claim 1 wherein the peroxyhydrate'salt is sodium percarbonate.-

4. The composition of claim 2 wherein the watersoluble waxy solid is selected from the group consisting of solid condensation products of 6-50 moles of ethylene oxide with one mole of any one of the following: (1) fatty alchols of 10-22 carbon atom chain length; (2) fatty acid amides of 10-22 carbon atom chain length and (3) alkyl phenols having 8-12 carbon atoms in the alkyl chain.

5. The composition of claim 2 wherein the watersoluble, waxy solid is the condensation product of one mole of coconut fatty alcohol and 45 moles of ethylene oxide.

6. The composition of claim 2 wherein the watersoluble, waxy solid is the condensation product of one mole of tallow fatty alcohol and 30 moles of ethylene oxide.

7. A process for preparing an oxygen bleach carrier comprising the steps of (a) dissolving a water-soluble, waxy solid, selected from the group consisting of water-soluble compounds which are waxy solids at temperatures between 18" C. and 38 C. and are selected from the group consisting of solid condensation products of 6-50 moles of ethylene oxide with one mole of any one of the following: (1) fatty alcohols of 10-22 carbon atom chain length; (2) fatty acid amides of 10-22 carbon atom chain length and (3) alkyl phenols having 8-12 carbon atoms in the alkyl chain,

6 in a volatile organic solvent having a boiling point between C. and C.,

,(b) slurrying into the solution formed in (a) an amount of peroxyhydrate salt which is 0.1 to 1.5 times the weight of the waxy water-soluble solid in the solution, said peroxyhydrate salt having a particle size between 0.210 mm. and 0.044 mm. and selected from the group consisting of the peroxyhydrates of the alkali metal borates, carbonates, silicates and phosphates, and

(c) spraying the slurry formed in (b) through an atomizing nozzle onto a falling curtain of granular borax having a bulk density between 0.03 g./cc. and 0.56 g./cc. and a particle size between 0.074 mm. and and 3.36 mm., the amount of said borax being from 0.05 to 1 times the combined weight of peroxyhydrate.

salt and waxy water-soluble solid.

8. The process in claim 7 wherein the peroxyhydrate salt is sodium perborate.

9. The process in claim 7 wherein the water-soluble, waxy solid is the condensation product of one mole of coconut fatty alcohol and 45 moles of ethylene oxide, and the solvent is ethanol.

10. The process in claim 7 wherein the water-soluble,

. waxy solid is the condensation product of one mole of tallow fatty alcohol and 30 moles of ethylene oxide and the solvent is methanol.

References Cited UNITED STATES PATENTS 3,018,258 1/1962 Moier et al ll7100 3,154,496 10/1964 Roald 25299 3,255,036 6/1966 Kramer et al. 117100 3,441,507 4/1969 Schiefer et al. 252186 3,449,254 6/1969 Suiter 25299 3,459,665 8/1969 Schiefer et al. 25299 RICHARD D. LOVERING, Primary Examiner I. GLUCK, Assistant Examiner US. Cl. X.R. 

